Last updated on October 23rd, 2023 at 08:28 pm
Spider mites are plant pests that occur both in houseplants and outdoors. We explain how you can recognize spider mites and how to fight them.
An infestation of spider mites can usually be recognized by the appearance of small white spots on the leaves and the appearance of small wool-like webs on the leaf axis and on the edges of the leaves.
Contents
Recognizing spider mites
The small arachnids grow between 0.1 and 0.8 millimeters in size, depending on the species, and, like all arachnids, have eight legs. The color of spider mites varies from light green, yellow-green to orange and rust-red depending on the color of the infested plant as well as the time of year.
Without a magnifying glass, spider mites are actually hard to spot. An infestation is more likely to be noticed by the damage done or the webs of the spider mites.
An infestation of spider mites can usually be recognized by the appearance of small white spots on the leaves and the appearance of small wool-like webs on the leaf axis and on the edges of the leaves.
Recognizing spider mites
The small arachnids grow between 0.1 and 0.8 millimeters in size, depending on the species, and, like all arachnids, have eight legs. The color of spider mites varies from light green, yellow-green to orange and rust-red depending on the color of the infested plant as well as the time of year.
Without a magnifying glass, spider mites are actually hard to spot. An infestation is more likely to be noticed by the damage done or the webs of the spider mites.
Spider mites prefer warm and dry air. Therefore, in winter they are found mainly on houseplants that are located in heated rooms. In summer, the pests also besiege garden and balcony plants as well as greenhouses.
However, houseplants can also be attacked by spider mites in summer. The female spider mites lay up to 100 eggs in their lifetime. Only three days after laying the eggs, the spider mite offspring hatch. This in turn is capable of reproducing after just one to a maximum of three weeks. Accordingly, spider mites spread quickly.
Damage caused by the spider mite
Spider mites not only form unattractive fine webs on the leaf axils and edges, they also damage the infested plants primarily through their sucking activities. With their piercing-sucking mouthparts, spider mites penetrate the underside of leaves and suck out the leaf cells. This can be recognized by silvery white dot-like spots on the leaf.
The saliva of the spider mite also contains a toxin that further damages the plants. The infested leaves begin to curl, dry out and eventually die. Furthermore, spider mites can transmit viruses that are harmful to plants.
Spider mites are not exactly choosy about their host plants. However, they prefer already weakened plants.
Fruit trees as well as berry bushes and vines are particularly frequently infested outdoors. In the greenhouse, vegetable plants are primarily on the spider mite’s menu:
- Cucumbers
- Beans
- Tomatoes
- Chili
In the room, on the other hand, spider mites are conceivable on almost any plant.
By the way, unlike their congeners, orchid spider mites do not form webs on the infested plant. At only 0.1 millimeters, they are almost impossible to see with the naked eye. However, the damage pattern on the leaves is the same as that of other spider mite species.
Combating spider mites
Whether indoors or outdoors, if you have noticed a spider mite infestation, you need to act quickly. One first aid measure is to treat with water. Shower the affected plants generously. However, be careful when doing so. Otherwise, the plants may be damaged. During this treatment, be sure to also wet the underside of the leaves with water.
In general, it is important to increase the humidity of the air. Spider mites prefer a dry climate. As a preventive and long-term treatment, you can regularly protect your plants from spider mites with water from a spray bottle (for houseplants) or hose (in the garden). In addition, you have proven small water bowls directly next to the plants. The evaporation of the water increases the humidity directly around the plants. However, there is never a hundred percent guarantee of success.
An infested plant must be immediately isolated from all other (hopefully not yet affected) plants.
Home remedies against spider mites
- Nicotine: Nicotine is a time-honored pesticide and, among many other pests, also helps against the spider mite. Mix some cigarette ash with water and water infested plants with it.
- Rapeseed oil: To combat spider mites with rapeseed oil, pour it pure into a small spray bottle and gently wet the leaves with it. Alternatively, you can also use tea tree oil. However, this should be strongly diluted (10 – 15 drops to 0.5 l of water). Infested plants are sprayed with it several times a day.
- Soap-spirit mixture: somewhat more radical is the fight against spider mites with a mixture of one liter of hot water, 20 grams of soap and 30 milliliters of methylated spirits. After cooling, fill the solution into a spray bottle and wet the plant generously with it. Especially do not forget about the undersides of the leaves.
- Furthermore, you can use various natural predators such as lacewing larvae against spider mites. And also the trade offers a wealth of different products that can help against spider mites.
- Generally speaking, not every (home) remedy is suitable for every plant. It is better to test the method of your choice on a small area first.
Spider mites are annoying and above all persistent. However, infested palms are not automatically lost. With a little patience and perseverance, you can get rid of the pests.